1. Field of the Invention
The present application relates generally to rotor hub assemblies, and more particularly, to a rotor hub assembly having a damper.
2. Description of Related Art
Conventional rotor hub assemblies are well known in the art for effectively controlling directional movement of a rotary aircraft. Articulated hub assemblies include two or more rotor blades that flap, feather, lead, and lag independently of each other. The hub assemblies typically include a horizontal hinge, called the flapping hinge, which allows the blade to move up and down. This movement is called flapping and is designed to compensate for dissymmetry of lift. The vertical hinge, called the lead/lag or drag hinge, allows the blade to move back and forth. This movement is called lead/lag, dragging, or hunting.
Conventional rotor hub assemblies typically include dampers operably associated with the horizontal and/or vertical hinge. The damper compensates for the acceleration and deceleration created by the rotor during flight. Specifically, the damper is configured to absorb the forces of the rotor blades and to maintain the frequency of the lead/lag motion within a desired range.
Conventional dampers include a single damping ratio, which is an undesired during different flight conditions. For example, the spring rate chosen for a lead/lag damper is a compromise between the value required for the desired in-plane stiffness and a value that reduces load and fatigue on the rotor and other aircraft components.
Although great strides have been made in rotor hub assemblies, many shortcomings remain.
While the assembly and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims.